Motorcycle gas tank

[nitsuj]

I have to make a few welds on a gast tank. It's new, so fumes aren't an issue. Some, not all of the welds will have to hod gas though. I'd much rather be able to do this myself. I hate farming work out. So heres my question, can a decent, air tight weld be made in this kind of thin metal with my HH135? Does it need to be tig welded? I'm sure tig would be optimum, but as I said, I hate farming this kind of stuff out, and I don't have a tig machine. I have plenty of tanks to practice on. Any chance I can do this without ending up woth gas puddles when I'm all done?

[Jerry]

Definitely this can be done with yuor machine, I would run a little hotter to make sure I have good penetration at all stops and starts.

Yes tig would be ideal though. Good luck bud.

[Roger]

The real question is can it be welded by you without leaks. Some pictures of your welds will give us a clue. Even if you can make near perfect welds the problem is your starts. You need to learn near invisible starts at end of your last weld. Start up to 1/4" past end of your last weld then quickly whip it back onto end of last weld and continue over the little tack start with the rest of your weld. This way will have hot start with no pin holes at start. Test welds by filling it with water. After your tired of tying to make it leak free coat inside of tank with sealant. Good sanding, body filler, paint and it will look like you knew what your doing. Need good fuel filter to catch all your mistakes before they damage fuel system.

Ok, I figure if your asking is it possible you need more practice to know you can do it. While your practicing look at back side of welds to see penetration and what crap you will be leaving in tank.

TIG or gas weld would be my first Choice

[nitsuj]

Well, I knew my skills would come into play, but I didn't figure anyone on a welding message forum could do much to help that. I had planned on coating the tank, and I had planned on running a filter. The rest of your suggestions were good ones, and I'll be trying them. Like I said, I have practice tanks, so I won't try it on my good one until I got it down on the old ones. Would you say I'd be nuts to even bother trying this with solid wire and no gas? That was my intention, I figured penatration would be better. But I suppose I could rustle up a tank and some new wire if you think the'd be better.

[MAC702]

Originally posted by nitsuj
Would you say I'd be nuts to even bother trying this with solid wire and no gas? That was my intention, I figured penatration would be better. But I suppose I could rustle up a tank and some new wire if you think the'd be better.

Either this was a typo, or yes, you'd be incredibly nuts. You'll want C25 gas, 75% Ar, 25% CO2. And you'll probably want .023 solid wire.

[MPK]

I have built a few gas tanks over the years, one 240 gal. size, and I always test them with air before I ever put gas in. I have never had a leak that way. You only need about 2 lbs of air to do this. While you have the air in, put on a little soapy water on the weld and if you have a leak it will bubble. It's surprising how little air it takes. On a large tank if the sides are flat like on a square tank if you go more than 2 lbs the sides will start to bulge. Even on a small oval tank , for safety I wouldn't go much more than 2 lbs air pressure.

[Roger]

Try welding with solid wire and no shilding gas. To start arc will need higher volts. Your welds will look like swiss cheese.
You nuts.

Self shielding flux core wire will be much harder than solid wire with no shielding gas as probably have too much penitration to weld with control. You would have to manually pulse the weld. Likely to get more holes in weld.

[nitsuj]

Yeah, I meant flux core, and no gas, not solid wire. Typo.

[Double D]

Originally posted by nitsuj
Yeah, I meant flux core, and no gas, not solid wire. Typo.

Nitsuj,
I welded a bunch of motorcycle tanks, always with 75/25 and ER70S6 Wire(0.24). Jerry has the right idea, Its not as easy as it sounds so practice your welds to perfection. Make sure you do not have any pressure on the tank during your dry welding process(as long as gas has not be in it). And make sure you pressure check the tank before use. Personally i would not weld it with flux core go get the tank.

Be safe
Double D